Fix flipped logic for handling memdiskfind

Commit 07d13d4 accidentally flipped
the logic for handling memdiskfind, causing erroneous messages and a
four second boot delay.

Flip the logic again to correct it.

Thanks to Marcel Partap for reporting it.

Signed-off-by: Benjamin Drung <benjamin.drung@profitbricks.com>

components/9990-main.sh

@@ -52,7 +52,7 @@ Live ()
 		else
 			if [ -x /usr/bin/memdiskfind ]
 			then
-				if ! MEMDISK=$(/usr/bin/memdiskfind)
+				if MEMDISK=$(/usr/bin/memdiskfind)
 				then
 					# We found a memdisk, set up phram
 					# Sometimes "modprobe phram" can not successfully create /dev/mtd0.